This isn't technically a guide. I find that everyone has their own personal way of healing, you may find my spec to be inefficient and I may find yours to be the same. I'm just going to breakdown how I've been playing this quite simple and effective healing build in dungeons.
Light of Redemption
Marked by the Light
Sign of Wrath
Light of Redemption
Diving Favor cast on self first (I'll always cast on tank and the two squishiest dps)
Wrathful Exuberence (cast on tank)
Nyol's Hope. Strong CD increasing healing done for 5 next single target heals. Use for tank.
Fullness of life. Strong ST heal, primarily used for tank but can be situational
Healer's Haste. Reduces cast time of next 5 healing spells. 30%. Cast times are already below the GCD, I haven't actually used this once.
Healer's Covenant. Reduces damage taken by 40%. Helpful when you use Reverent Supplication.
Touch the Light. One instant cast, reduced mana. Best used on Cruical Invocation for mana cost.
Urgency. Movement speed +50% for 10s on a single target.
Renewed Altruism. Resets cooldown on all sentinel abilities except Lifes return (battle res).
Vigilance. 2min CD off the GCD. Big heal on killing blow or if target drops below 20%.
61 points into Sentinel
5 into Spirit Guidance and 2 into Intensity for Purifier
5 into Strength of the Deep and 3 into Ocean's Bounty for Warden
Keep up Flame Lance as much as possible. Obviously don't use it in times where a single GCD means tank death. It has a 2.0s cast time but can be instant with Faith's Reward.
How I AoE with this build!
Keep up 3 stacks of healing flood on the group at all times. If there is a lull in the damage but you know something is coming, you can pre-cast healing spray. During group damage, spam Healing Communion but don't just keep one person as a target, cycle through the group. The person you're targeting when you cast any invocation, including Legendary Healing Communion, will have Legendary Banish, and Lights Redemption applied to them. Legendary Light of Redemption will heal targets this buff on them whenever you cast an invocation. If you need to spot heal someone, use Crucial Invocation on them. Mana is not an issu when spamming Healing Communion as it costs no mana and restores mana when used.
How I tank heal
I honestly just keep healing flood and 3 stacks of Healing Flood on the tank and spam Healing Invocation or, if I need harder hitting heals, I'll cast Crucial Invocation. If the tank isn't getting hit very hard, i'll even spam Healing Communion to keep my mana. However, if the tank is getting hit hard and you need to spam Crucial Invocation, refer to the mana section below.
Healing While Moving!
With the Faith's Reward mastery, you can be effective on the move as well!. Although you need to weave in a wasted GCD in between every cast, you can continuously move while healing. This is particularly useful in dungeon groups where the tank likes to pull tons of mobs and not wait for you. Just cast Healing flood once, then use Crucial Invocation for ST, or Healing Communion for AoE. Any time you cast Healing Flood you gain 3 stacks of Faith's reward, making pretty much all of your sentinel healing spells instant cast. (Probably a bug, but may as well use it to advantage now).
Mana in this build
Mana for this build can be an issue when you're healing squishier tanks, until you get more gear. I found, before I became pimped out with full dungeon gear and 70 essences, that I had to spam Crucial Invocation which would drain your mana. Now I'm in a position where I can spam Subtle Invocation on most tanks, or even Healing Communion.
If you ever run into mana issues during a fight, just use Reverent Supplication, cast a few quick cast heals and be on with the fight. Certain times though, you may need to use this while the tank is getting destroyed (I.E. Pull to many mobs for their gear). If this happens and you're low on mana, use Reverent Supplication, cast a few spells, then remove the buff so your heals don't get gimped by 50%.
NOTE: During this time you can also make use of Fullness of Life for a huge tank heal, Vigilance to prevent 1 death or if they drop below 20%. I also suggest, if you can, saving Healer's Covenant for when you need to go into Reverent Supplication during hard times.
I think that's all I can say. I won't post HPS numbers because those are a little moot. I've been anywhere from 10k to 90k depending on how much damage the group is taking, or if there is a primalist tank in the group. If there is a primality tanking you can kind of just afk since they do your job for you.
PM Lindrinsi@Greybriar if you have any questions or feel free to reply with a post!